Can I assert a lien over a client’s passport?
Until the end of 2009 the accepted view was that you could not assert a lien over an Australian passport, as it is the property of the Commonwealth Government and you could only have a lien on the client’s property.
However, the December 2009 New South Wales Court of Appeal decision in Xu v Council of the Law Society of NSW  NSWCA 430 establishes that you can have a lien on a client’s passport, as against the client although not as against the Commonwealth government – see judgment of Handley JA at paragraphs 52-57. A court may of course order you to deliver the passport to it if required in connection with granting of bail – see paragraph 57. There are circumstances where you may not be entitled to assert a lien where this would restrict the client’s right to travel outside of Australia - see minority judgment of Basten JA at paragraphs 18-20.
Note that this case refers to sections 6A and 9A(1), (2) of the Passports Act 1938 (Cth) which were in force at the time of the relevant conduct in mid 2004. The relevant provisions since 2005 have been sections 54 and 32(4), (5) of the Australian Passports Act 2005 (Cth) which are in very similar terms.
For New Zealand passports it may still be the case that you cannot have a lien. Unlike the Australian position, New Zealand has a statutory provision which prohibits use of a passport as a security, pledge or deposit – see paragraphs 17 and 51 of the Xu case, s.33 of the Passports Act 1992 (NZ) and Vallant Hooker & Partners v Proceedings Commissioner  2 NZLR 357 at 363 (HC) (available from Supreme Court Library: Document Delivery).